Objects gray when rendered
It looks to me like you have two materials on that object. I'm guessing the second material (the one you edited to have some color) is not assigned to the mesh anywhere.

In edit mode select the whole object A A. Now click on the material in the list (yours is called "Material.002") and press the Assign button.




Now if you are not using the first material for anything you can simply remove it. Go to Object mode (you can not remove material slots in edit mode), with the first material selected click on the minus button on the right.